In a semiconductor device manufacturing sequence, there is a film forming process for forming a nitride film such as a silicon nitride film (SiN film) or the like as an insulating film on a semiconductor wafer represented by a silicon wafer. A chemical vapor deposition (CVD) method is widely used for such a SiN film forming process.
On the other hand, in recent years, along with the advancement of miniaturization and high integration of semiconductor devices, to improve characteristics, a SiN film is formed by sequentially supplying gases as in an atomic layer deposition (ALD) method capable of forming a good quality film at a lower temperature than that of the film formation by the conventional CVD method. In the case of forming the SiN film by the ALD method, for example, a SiN film having a predetermined film thickness is formed by causing a Si raw material to be adsorbed onto a substrate to be processed, subsequently supplying a nitriding gas so as to react with the Si raw material, forming SiN at an atomic layer or molecular layer level, and repeating the above steps a predetermined number of times.
As a method of forming a SiN film by an ALD method, there has been proposed a technique in which a dichlorosilane (DCS: SiH2Cl2) gas, which is a type of Si raw material gas, and an ammonia (NH3) gas, which is a type of nitriding gas, are alternately supplied, and when supplying the NH3, high frequency power is applied so as to generate plasma to promote a nitriding reaction.
Since the apparatus configuration becomes complicated in the case of using plasma, it has been studied to form, as in a thermal ALD method or the like, a SiN film by a plasma-less sequential gas supply.
By the way, when a nitride film such as a SiN film or the like is grown by an ALD method or a CVD method on a structure in which two or more different base films are exposed, it is required to selectively grow a nitride film only on a specific base film.